High propellant flow through a Hall thruster was thought to compromise its efficiency, but new experiments suggest it could power a manned mission to Mars.
Hall thrusters, an efficient electric propulsion device widely used in orbit, were thought to have to be large to produce large amounts of thrust. Now, new research from the University of Michigan suggests that smaller Hall thrusters can generate much more thrust, making them potential candidates for interplanetary missions.
“It was previously believed that only a certain amount of current could be passed through the thruster region, which translates directly to the amount of force or thrust that can be produced per unit area,” said today, Maryland. He led a new Hall Thruster study to be presented at the AIAA SciTech Forum at National Harbor.
His team pushed the envelope by operating a 9-kilowatt Hall thruster at up to 45-kilowatt while maintaining about 80% of its nominal efficiency. This increased the amount of force generated per unit area by almost a factor of 10.
Whether you call it a plasma thruster or an ion drive, electric propulsion is great for interplanetary travel, but science is at a crossroads. Hall thrusters are a well-proven technology, but an alternative concept known as magnetoplasma dynamic thrusters promises to pack more power into a smaller engine. However, they are still unproven in many respects, including longevity.
Hall thrusters were thought to be uncompetitive because of the way they worked. The propellant, typically a noble gas such as xenon, moves through a cylindrical channel accelerated by a strong electric field. Proceed backward to generate forward thrust. But before we can accelerate the propellant, we need to lose some electrons to give it a positive charge.
Electrons accelerated by the magnetic field and running in a ring around that channel (what Jones described as a “buzz saw”) knock electrons off propellant atoms, turning them into positively charged ions. However, calculations suggest that as the Hall thruster attempts to drive more propellant through the engine, the thundering electrons within the ring are knocked out of formation, destroying its “buzzsaw” function. I got
“It’s like trying to chew more than you can chew,” Jorns says. “Buzz’s saw can’t handle that much material.”
Additionally, the engine gets very hot. Jorns’ team put these beliefs to the test.
“We named the thruster H9 MUSCLE because, essentially, we took the H9 thruster and spun it up to 11 to make a muscle car. , up to 100,” says Leanne Su. She is a PhD student in aerospace engineering presenting her research.
They tackled the heat problem by cooling with water. This gave us an idea of how big a problem the breakdown Buzz saw could be. H9 MUSCLE operates at up to 37.5 kW using the conventional propellant, xenon, with an overall efficiency of about 49%, not far from his 62% efficiency at 9 kW of design power.
Nested Hall thrusters like the X3 (also partly developed by UM) have been investigated for interplanetary cargo transport, but are much larger and heavier, making them unsuitable for transporting humans. Have difficulty. Now regular Hall thrusters are back on the table for manned travel.
Jorns says that when Hall thrusters operate at these high powers, the cooling problem will require a space-consistent solution. Still, he is optimistic that individual thrusters could be arranged in an array that he would operate at 100 to 200 kilowatts and provide megawatts worth of thrust. This could allow him to travel 250 million miles to Mars on a manned mission, even on the far side of the Sun.
The team hopes to pursue cooling issues similar to those in developing both Hall thrusters and magneto-plasmadynamic thrusters on Earth, where few facilities are available to test Mars mission-level thrusters. The amount of propellant ejected from the thrusters is too fast for the vacuum pump to keep the conditions in the test chamber space-like.
Original: Plasma thrusters used on satellites could be much more powerful
Than: University of Michigan
